Some regulations require that an aircraft turbomachine should be capable of resisting fire for a minimum duration, while preventing the supply of combustible fluid, typically lubricant, to the fire.
Various turbomachine equipment is supplied with lubricant by, a lubrication system that generally allows a sufficient lubricant flow to pass to cool the turbomachine in case of fire.
However, when the lubricant flow drops to become too low during a fire, the oil flow to this equipment has to be limited and/or a specific fire protection has to be provided for this equipment. These specific fire protection systems have the disadvantage of being large and heavy.
It is also known that the flow of lubricant in the case of a fire can be limited by isolating the lubricant tank by a cutoff valve controlled by a regulation system, at least until the fire is definitively extinguished.
Nevertheless, the regulation system of some turbomachines or some aircraft may not be available during the fire to control closure of this cutoff valve, for example as confirmed in application EP 1 936 122, which can generate unwanted cutoffs even when there is no fire.
Therefore there is a need to isolate a turbomachine combustible fluid tank only in the case of a fire, while limiting availability requirements of a regulation system, and the mass and dimensions of the turbomachine.